Mateusz Gładysz FESSH prep

FESSH prep Tendon injuries Extensor tendon zone I — classification, splinting, indications for fixation and sequelae

Mallet finger

Last reviewed v1.0

FESSH-032Tendon injuries●○○ basic

Regarding mallet finger (zone I extensor tendon injury):

  1. 1.In Doyle's classification of mallet injuries, type IV is the bony mallet; subtype B involves 20–50% of the articular surface and subtype C more than 50%.

  2. 2.Standard non-operative treatment of a closed mallet finger is continuous extension splinting of the distal interphalangeal joint for six to eight weeks with the proximal interphalangeal joint left free.

  3. 3.Randomised trials show that custom thermoplastic splints produce significantly less residual extensor lag than prefabricated Stack splints.

  4. 4.A mallet fracture involving more than one-third of the articular surface is an absolute indication for operative fixation.

  5. 5.An untreated chronic mallet finger can lead to a secondary swan-neck deformity.

FESSH marking: +1 per correct statement, 0 for blank, −1 for incorrect. Click the same TRUE/FALSE button twice to clear it.

Question ID
FESSH-032
First published
Last reviewed
Version
v1.0
Answer key and explanations — open after answering

  1. 1. In Doyle's classification of mallet injuries, type IV is the bony mallet; subtype B involves 20–50% of the articular surface and subtype C more than 50%.

    True

    Doyle's classification separates closed tendinous injury (type I), open laceration (type II), open deep abrasion with loss of skin and tendon substance (type III) and bony mallet (type IV). Type IV is subdivided into A, a transphyseal fracture in children, B, a fracture involving 20–50% of the articular surface, and C, a hyperextension injury with more than 50% of the articular surface, giving six categories in all. The scheme does not itself encode volar subluxation of the distal phalanx, which is a separate radiographic finding that drives treatment.

    • Salazar Botero S, Hidalgo Diaz JJ, Benaïda A, Collon S, Facca S, Liverneaux PA. Review of Acute Traumatic Closed Mallet Finger Injuries in Adults. Arch Plast Surg. 2016;43(2):134-44. PMID 27019806
    • Lu YH, Wu CC, Hsieh CP. A Modified Pull-out Wire Technique for Acute Mallet Fracture of the Finger. Indian J Orthop. 2018;52(6):611-615. PMID 30532301

  2. 2. Standard non-operative treatment of a closed mallet finger is continuous extension splinting of the distal interphalangeal joint for six to eight weeks with the proximal interphalangeal joint left free.

    True

    Splinting the distal interphalangeal joint in extension for six to eight weeks yields good results with minimal morbidity in the majority of patients; the trials in a systematic review immobilised acute injuries for six weeks and chronic ones for eight, extending the period when a lag persists. The splint is worn continuously, because any flexion of the joint during the period effectively restarts healing, and the proximal interphalangeal joint is left free in standard mallet splinting; this clinical recommendation should not be interpreted as proof that PIP position never affects terminal tendon excursion. The joint is splinted in neutral or only slight hyperextension: dorsal skin blanches at about half of the available passive hyperextension and splinting beyond that risks pressure necrosis.

    • British Society for Surgery of the Hand. Mallet Injuries – standards for treatment. 2020.
    • Bendre AA, Hartigan BJ, Kalainov DM. Mallet finger. J Am Acad Orthop Surg. 2005;13(5):336-44. PMID 16148359
    • Valdes K, Naughton N, Algar L. Conservative treatment of mallet finger: A systematic review. J Hand Ther. 2015;28(3):237-45; quiz 246. PMID 26003015
    • Schweitzer TP, Rayan GM. The terminal tendon of the digital extensor mechanism: Part II, kinematic study. The Journal of hand surgery. 2004;29(5):903-8. PMID 15465242
    • Rayan GM, Mullins PT. Skin necrosis complicating mallet finger splinting and vascularity of the distal interphalangeal joint overlying skin. The Journal of hand surgery. 1987;12(4):548-52. PMID 3611652

  3. 3. Randomised trials show that custom thermoplastic splints produce significantly less residual extensor lag than prefabricated Stack splints.

    False

    In a multicentre randomised trial comparing Stack, dorsal aluminium and custom thermoplastic splints worn continuously for eight weeks there was no difference in extensor lag at 12 or 20 weeks; treatment failure occurred in 23.8% of the Stack and dorsal groups and none in the thermoplastic group, while patient satisfaction and pain did not differ significantly. A second randomised trial and the Cochrane review likewise found no difference in lag by splint design. Adherence to continuous wear, not the device, drives the outcome, and the splint must be robust enough for daily use.

    • O'Brien LJ, Bailey MJ. Single blind, prospective, randomized controlled trial comparing dorsal aluminum and custom thermoplastic splints to stack splint for acute mallet finger. Arch Phys Med Rehabil. 2011;92(2):191-8. PMID 21272714
    • Handoll HH, Vaghela MV. Interventions for treating mallet finger injuries. Cochrane Database Syst Rev. 2004;2004(3):CD004574. PMID 15266538

  4. 4. A mallet fracture involving more than one-third of the articular surface is an absolute indication for operative fixation.

    False

    The one-third rule is traditional but not evidence-based. Wehbé and Schneider found that mallet fractures remodelled and did well irrespective of treatment, that surgery was difficult and unreliable with greater morbidity, and that most could be treated conservatively regardless of fragment size or subluxation. A randomised trial of splinting versus extension-block pinning for fragments exceeding one-third of the joint surface without subluxation found no difference in extensor lag at six months and better motion after splinting, although three splinted patients developed secondary subluxation, so radiographic follow-up during splinting is advised. Irreducible volar subluxation of the distal phalanx is the one widely accepted operative indication, typically managed by extension-block pinning.

    • Wehbé MA, Schneider LH. Mallet fractures. J Bone Joint Surg Am. 1984;66(5):658-69. PMID 6725314
    • Thillemann JK, Thillemann TM, Kristensen PK, Foldager-Jensen AD, Munk B. Splinting versus extension-block pinning of bony mallet finger: a randomized clinical trial. J Hand Surg Eur Vol. 2020;45(6):574-581. PMID 32338190

  5. 5. An untreated chronic mallet finger can lead to a secondary swan-neck deformity.

    True

    Persistent terminal tendon dysfunction can alter the balance of the extensor mechanism, producing PIP hyperextension with DIP flexion in some patients. This secondary swan-neck deformity is a possible late complication of chronic mallet finger, not an inevitable natural history. Published surgical series document the complication but do not determine its incidence among all untreated mallet injuries.

    • Rode MM, Mullen BL, Zhu AQ, Helsper EA, Moran SL. Surgical Management of Swan Neck Deformity Following Mallet Finger Injury: A Review of 25 Patients Over 20 Years. Hand (New York, N.Y.). 2025;20(2):197-202. PMID 37872782
    • Suroto H, Aprilya D, Prajasari T, Nugraha AB. Treatment of chronic mallet finger with swan neck deformity using a modified Spiral Oblique Retinacular Ligament (SORL) reconstruction procedure: A case series and technical note. International journal of surgery case reports. 2023;104:107925. PMID 36796158